Abstract: In order to find out the mechanical behavior of space grid structures in fire, the heat transfermechanics coupling finite element model for the fire performance of space grid structures in fire was proposed in this paper, and the influence of the fire scenario on the fire performance, the deformation mode, the mechanical principle and the stress and strain redistribution of the grid structures were also studied.The results show that the scenario has obvious influence on the deformation of the space grid structures, and the evident tensile membrane action occurs in the later of the fire in the central scenario, and the ultimate state of space grid structures should be based on its deformation limit.